Magnetic recording medium and magnetic memory apparatus

Abstract

Disclosed is a magnetic memory apparatus which comprises a patterned magnetic recording medium in which multilayered films each having a first magnetic layer, a nonmagnetic metal layer or a nonmagnetic insulating layer and a second magnetic layer deposited discretely on a conductive electrode layer formed on a substrate, and a cantilever array having a plurality of cantilevers each having a conductive chip at its distal end. This provides a magnetic solid memory apparatus that has a large memory capacity and a super fast transfer rate, the merits of a hard disk apparatus, and a nanostructure and low power consumption, which are the merits of a semiconductor memory.

1. A magnetic memory apparatus comprising:
 a patterned magnetic recording medium in which multilayered nanostructures each having a first magnetic layer, a nonmagnetic metal layer or a nonmagnetic insulating layer and a second magnetic layer laminated in that order on a conductive electrode layer formed on a substrate are laid out apart from one another at substantially even pitches; and  
 a cantilever array in which cantilevers having conductive chips at distal ends are laid out in an array and apart from one another in such a way as to be associated with said nanostructures, whereby information is written or read by a current supplied from that one of said conductive chips which is associated with a desired one of said nanostructures as that conductive chip is put in contact with said desired nanostructure.  
 
     
     
       2. The magnetic memory apparatus according to  claim 1 , wherein the patterned magnetic recording medium includes pillar-like nanostructures each comprising a multilayered film showing a tunneling magnetoresistance effect or a multilayered film showing a giant magnetoresistance effect are surrounded by insulators in such a way as to be laid out apart from one another at substantially even pitches and are provided on a conductive electrode layer formed on a substrate. 
     
     
       3. A patterned magnetic recording medium in which pillar-like nanostructures each comprising a multilayered film having a lamination of a multilayered film showing a tunneling magnetoresistance effect and a multilayered film showing a giant magnetoresistance effect are surrounded by insulators in such a way as to be laid out apart from one another at substantially even pitches and are provided on a conductive electrode layer formed on a substrate. 
     
     
       4. A patterned magnetic recording medium in which pillar-like nanostructures each comprising a multilayered film showing a tunneling magnetoresistance effect or a multilayered film showing a giant magnetoresistance effect are surrounded by insulators in such a way as to be laid out apart from one another at substantially even pitches and are provided on a conductive electrode lever formed on a substrate, wherein said multilayered film showing said tunneling magnetoresistance effect comprises a multilayered film having a first magnetic layer, a nonmagnetic insulating layer and a second magnetic layer laminated in that order, said multilayered film showing said giant magnetoresistance effect comprises said second magnetic layer, a nonmagnetic metal layer and a third magnetic layer laminated in that order, and said second magnetic layer constituting said multilayered film showing said tunneling magnetoresistance effect serves as said second magnetic layer constituting said multilayered film showing said giant magnetoresistance effect. 
     
     
       5. The magnetic memory apparatus according to  claim 2 , where the patterned magnetic recording medium comprising means for fixing a direction of magnetization of one of magnetic layers constituting said multilayered film showing said tunneling magnetoresistance effect or said multilayered film showing said giant magnetoresistance effect to one direction. 
     
     
       6. The patterned magnetic recording medium according to  claim 4 , comprising means for fixing a direction of magnetization of said third magnetic layer to one direction. 
     
     
       7. The magnetic memory apparatus according to  claim 5 , wherein the means for fixing said direction of magnetization to one direction is an antiferromagnetic film. 
     
     
       8. A magnetic memory apparatus comprising:
 a patterned magnetic recording medium in which nanostructures each comprising a multilayered film showing a tunneling magnetoresistance effect and/or a multilayered film showing a giant magnetoresistance effect are surrounded by insulators in such a way as to be laid out apart from one another at substantially even pitches and are provided on a conductive electrode layer formed on a substrate; and  
 a cantilever array in which cantilevers having conductive chips at distal ends are laid out in an array and apart from one another in such a way as to be associated with said nanostructures, whereby information is written or read by a current supplied from that one of maid conductive chips which is associated with a desired one of said nanostructures as that conductive chip is put in contact with said desired nanostructure.  
 
     
     
       9. A magnetic recording method which uses a patterned magnetic recording medium in which nanostructures each comprising a multilayered film showing a tunneling magnetoresistance effect and/or a multilayered film showing a giant magnetoresistance effect are surrounded by insulators in such a way as to be laid out apart from one another at substantially even pitches and are provided on a conductive electrode layer formed on a substrate, and a cantilever array in which cantilevers having conductive chips at distal ends are laid out in an array and apart from one another in such a way as to be associated with said nanostructures, and writes digital information by inverting magnetization with 1 being a state where a resistance of said multilayered film is high while 0 is a state where said resistance is low, using a current supplied from that one of said conductive chips which is associated with a predetermined one of said nanostructures as that conductive chip is put in contact with said predetermined nanostructure. 
     
     
       10. A signal reading method which uses a patterned magnetic recording medium in which nanostructures each comprising a multilayered film showing a tunneling magnetoresistance effect and/or a multilayered film showing a giant magnetoresistance effect are surrounded by insulators in such a way as to be laid out apart from one another at substantially even pitches and are provided on a conductive electrode layer formed on a substrate, and a cantilever array in which cantilevers having conductive chips at distal ends are laid out in an array and apart from one another in such a way as to be associated with said nanostructures, end detects a level of a resistance of each multilayered pillar by putting that one of said conductive chips which is associated with a predetermined one of said nanostructures in contact with said predetermined nanostructure and causing a current whose value is smaller than that of a current by which magnetization of said multilayered film is inverted to flow from said conductive chip. 
     
     
       11. The magnetic memory apparatus according to  claim 1 , wherein a number of said multilayered nanostructures substantiality equals a number of said cantilevers having the conductive chips at the distal ends thereof, wherein each respective one of said multilayered nanostructures is associated with a predetermined differing respective one of said cantilevers, whereby information is written or read by a current supplied from that one of said conductive chips which is associated with a desired one of said nanostructures as that conductive chip is put in contact with said desired nanostructure. 
     
     
       12. The magnetic memory apparatus according to  claim 8 , wherein a number of said multilayered nanostructures substantially equals a number of said cantilevers having the conductive chips at the distal ends thereof, wherein each respective one of said multilayered nanostructures is associated with a predetermined differing respective one of said cantilevers, whereby information is written or read by a current supplied from that one of said conductive chips which is associated with a desired one of said nanostructures as that conductive chip is put in contact with said desired nanostructure. 
     
     
       13. The magnetic memory apparatus according to  claim 9 , wherein a number of said multilayered nanostructures substantially equals a number of said cantilevers having the conductive chips at the distal ends thereof, wherein each respective one of said multilayered nanostructures is associated with a predetermined differing respective one of said cantilevers, whereby information is written or read by a current supplied from that one of said conductive chips which is associated with a desired one of said nanostructures as that conductive chip is put in contact with said desired nanostructure. 
     
     
       14. The magnetic memory apparatus according to  claim 10 , wherein a number of said multilayered nanostructures substantially equals a number of said cantilevers having the conductive chips at the distal ends thereof, wherein each respective one of said multilayered nanostructures is associated with a predetermined differing respective one of said cantilevers, whereby information is written or read by a current supplied from that one of said conductive chips which is associated with a desired one of said nanostructures as that conductive chip is put in contact with said desired nanostructure.